The present invention relates to a reader-encoder of magnetic cards provided with a magnetizable track, comprising means for maintaining one such support in a determined position in contact with magnetic read-write means, and means for displacing a uniform rectilinear movement the read-write means along the magnetizable track of the information carrying support.
In rigid or semi-rigid magnetic card reader-encoders of this type, such as for example those used in banking transactions, the information is encoded magnetically on at least one magnetic track disposed to this end on one face of the card. The read-write means consist in known manner of a magnetic head which may either by fixed, or mobile. It is fixed in the case of "Swallowing" encoders in which the card moves with respect to the encoding means, or mobile in those encoders where the card is simply introduced into a slot and is recovered by the user after exploitation thereof.
The device according to the invention is included in the latter category. For the system to be reliable and in accordance with certain standards concerning the coding of credit cards, the relative speed of displacement between the magnetic head and the track must be linear and uniform with instantaneous variations less than 5%.
To filter the vibrations due to the drive motor, it is known, such as for example in record player decks, to connect the pulley of the motor to a first gear-down pulley, greater in diameter, by means of an elastic belt. However, the known devices, whether they be with gears, notched belts or endless screws, do not enable the standards in question to be respected and require devices for making up for mechanical clearances, which renders them complex and expensive.
It is an object of the device according to the invention to avoid these drawbacks whilst ensuring an instantaneous variation in speed, at carriage level, which does not go beyond 1.5%.